Hydraulic butt welder control



April 10, 1945. c. E. coATEs 2,373,226

HYDRAULIC BUTT WELDER CONTROL Filed Feb. 18, 1942 4 Sheets-Sheet l CLYDE E COATES April 1945. c. E. COATES HYDRAULIC BUTT WELDER CONTROL Filed Feb. 18, 1942 4 Sheets-Sheet 2 gin wanton E. COATES April 10, 1945. c CQATES 2,373,226

HYDRAULIC BUTT WELDER CONTROL Filed Feb. 18, 1942 4 Sheets-Sheet 4 gwue/wbo'a' CLYDE E COATES I w 1 ms. t

' deEOoa 'w ,0! i a m a lor-Win'ile of Ohio omen-i am tion, Warren. Ohio. a

Application February 18, 1942, Serial No. 431,364

V 22 Claims.

This invention relates to electric welding apparatus and more particularly to lin the movement oi the movable platen of a.

As is well under butt flash welding machine. stood in the art. such machines consist essentially or an insulated normally fixed paten having an electrode and means to'clamp one of the pieces to be welded in or to this electrode. and a movable platen also provided with an electrode and stockclamping apparatus. The movable platen is suitably guided for sliding movement toward and away from the hired platen and to accoln- 4 plish such relative movement, an actuator such as a motor driven cam orone or more hydraulic cylinders are connected to the movable platen. For reasons of better operational characteristics and greater facility of control, the hydraulic moving means is much preferred and the present invention is concerned, in its more speciflc as-l pects. with the control of the flow oi-hydraulic;

edgesof the stock pieces to be welded and to thereafter move the platen accelerated rate or travel to upset the edges of the stock pieces in eflecting the weld. This required cycle of operation presents substantial difficulties particularly in the larger machines as, for example, in machines employed to butt weld wide metal strip since large quantities or fluid and delivered under very high pressure thus making the upsetting fluid load and demand many times greater than the supply required to effect the flashing. Heretotore the practice has been to employ the same valve to meter and control the flow of the fluid to the platen cylinder for both flashing and upsetting and since the valve was eilected with precision either automatically or semi-automatically. Consequently optimum control over the welding cycle was not attained and the apparatus parts were unduly cumbersome and expensive.

forwardly at a highly the provision or an governing the flow platen cylinder of improved control system (or oi fluid under pressure to the a butt flash provided to sheet the flashing may be constructed an controlled with greater precision. This object is in' accordance which. as

quires but a relatively low rate or fluid flow.

making up the above describedgeneral method or o For example the pattern or the rate or change of the operaindependent adjustment oi the current cut-oil time with respect to the end oi the and thus contribute substantially to the quality of the work performed by the machine to which the control is applied.

uniform stock. The apparatus is so designed and constructed that the manual control of the entire operation may be effected normally by manipulation of a single lever and by reason of the arrangement and precision of the elements coupled with the lever, the operator can readily "feel the character of movement of the platen and thus acquire finesse in operating the machine.

Yet another object of the invention is the One oi the objects of the present invention is provision of a control system of the character ment of the invention. the same is accomplished by employing a controlling can of variable pattern and special construction and equipping the apparatus with means to vary the effect produced by said cam once its pattern is selected and locked.

The above and other obiects and advantages of the invention will become apparent from a consideration of the following detailed speciflcation and the accompsnyins drawings wherein there is specifically discloud a preferred embodiment of the invention.

In the drawings:

Figure l is a schematic representation of a hydraulically operated butt flash welder constructed in accordance with the principles of the invention;

Figure 2 is a detailed view of a portion of the control apparatus utilized in the preferred embodiment of the invention;

Figure 3 is a vertical section through the principal control valve of the apparatus:

Figure 4 is a horizontal section through the valve of Figure 3, the view illustrating the inner core of the valve rotated slightly from the position in which it is shown in Figure 3;

Figures 5 and 6 are longitudinal sections through a fluid pressure operated and a mechane ical operated relay valve, respectively, utilized in the apparatus; and

filter It and, in accordance with established commercial practice, is provided with integral pressure relief valves which discharge through cooler is back into sump 14. Normally pump it is operated continuously and when there is no demand for fluid. its entire output is bypassed through cooler 20.

An accumulator 21, which may be of a spring loaded type, but is preferably of the air loaded type in the case of larger machines, is interposed in the fluid supply line, which line extends to a rotary follow valve ll shown schematically in Figure l but in detail in Figures 3 and 4. Valve Ills provided with an inlet port 2!, an exhaust port a, an outlet 3i through which fluid flows to move the platen is in a forward direction or in a direction toward the fixed platen, and an outlet port 32 through which fluid flows to move the platen in the reverse direction.

Fluid is also conducted from the accumulator 21 to the pressure inlet port ll of a fluid pressure controlled dumping valve 33 shown schematical ly in Figure 1 but in detail in Figure 5. Valve a is provided with a control fluid inlet port I, an

exhaust port if, an outlet port 31 through which fluid flows to move platen ll forwardly, and an outlet port 38 through which fluid flows to move platen i5 backwardly.

Referring now to Figures 3 and 4, the rotary '0 follow valve 28 comprises a housing 39 and inner and outer rotors ll and ll, respectively, which are arranged to be independently rotated in a manner to be described hereinafter. Housing 30 is provided with an annular passage for and in a communication with each of the ports 29, 3| and Figures '1, 8 and 9 are plan, side and end views,

respectively. of a cam. construction utilized in the preferred and illustrated embodiment of the invention.

Referring first to Figure 2 of the drawings reference numeral It indicates the main frame of a butt flash welding machine and reference numeral ll designates a fixed platen carrying an electrode I! which platen and electrode are insulated at from the main body of the machine. is a movable platen l5 carrying an electrode l6. As is well understood in theart the pieces to be welded are rigidly clamped to the electrodes i2 and It by suitable mechanism carried by the respective platens. The heating and flashing current is supplied to the electrodes by a suitable tapped transformer i'l.

Referring to Figure l movable platen I5 is arranged to be actuated by a hydraulic cylinder is which is rigidly attached to the frame of the machine and which has its piston rod I! extending out of either end of the cylinder. One end of the rod is is arranged to be adiustably coupled to the platen I i, as shown, while the other end is threaded and provided with an adjustable nut 20, the purpose of which is to limit the inward movement of the platen II and consequently the iiial interval between the die electrodes i2 and Any suitable supply of fluid under pressure may be employed for operating the apparatus of the invention but for purposes of illustration a two-stage constant delivery pump 2| is shown as supplying fluid under pressure to a conduit 22 provided with a check valve 23. Pump 2| is supplied with fluid from a sunfp 24 through a Slidably mounted in suitable guides 14 0 ing at all times with openings through the side- 32. The lower part of housing 38 is provided with an annular chamber 4: in communication with the exhaust port II. Inner rotor ll has a longitudinal passage with openings communicatwall of outer rotor H, which last named openings are in turn in vertical register with the annular groove which is in communication with the inlet port 28. The lower end of rotor II is.

enlarged and provided with diametrically opposed bores adapted to slideably receive the bored shoes 43 which are spring pressed outwardly, as shown, to engage a cylindrical surface formed in the lower portion of rotor ll. Rotor ll is provided with diametrically opposed passages 44 and 45 which extend outwardly from the cylindrical surface aforesaid and up to the annular recess which communicates with port 32. spaced from passages 44 and N are the diametrically opposed passages 46 and 41 which extend from the cylindrical surface aforesaid to the annular recess in housing 39 which is coincident with the port 3|. A groove 48 in housing I! is aligned vertically with radially extending openings in rotor ll and with a groove in rotor 40 to collect and drain of! through passage is any fluid seepage which may occur; This prevents high pressure from reaching the packings of the valve.

with the parts of valve 2! relatively positioned as indicated in Figure. 4, no fluid will flow since the openings through shoes 43 are blocked off. If the inner rotor is now turned counter-clockwise, fluid will flow from inlet port 29 through shoes 43' and passages 40 and 41 to outlet ii to move the platen IS in a forward direction. If it is assumed that the outer rotor 4i begins to move .in the same direction shortly after the inner rotor-is rotated, it will be apparent that when rotor 4i overtakes rotor 4| and the two rotors resume their relative positions shown in Figure Angularly assassin 4, the flow of fluid will again cease Operation municates with port ll to allow for the return in the reverse direction is identical and in either flow or the fluid case it should be oserved that when the faces of Bypassing valve 18 is a conduit 83 having a shoes 43 are in position to supply fluid to one check valve 84 therein which allows a rapid reof the sets of passages 48, 4'! or M, 45, the pas- I turn flow of the fluid. Correlating Figures l sages of the other set are opened to the chamber and 2, when the plunger in valve 84 is not en- 4: to allow the fluid to escape from the contract gaged, the full line pressure acting on the rod ing end of the platen cylinder. end of cylinder it will move the piston to one In accordance with the illustrated embodiment end of the cylinder in which position the slide it of the invention, the inner rotor u or valve a (and the cam 60) will be in outer position with is arranged to be rotated by a slidably mounted the follower on arm 59 at the end "A or the cam It through a follower arm ii and a lever cam It. Upon actuation oi plunger '2, fluid will I! rigidly clamped to the rotor. The outer rotor be metered through valve 18 and .by reason of or the valve 20 is arranged to be rotated upon the larger efl'ective area of the piston in the adsliding movement of the platen it through toggle lo jacent end of cylinder 16, the cam III will be linkage 53. For this purpose a bracket II is admoved in the direction indicated in Figure 2 justably secured to the platen I8 and slidably at a rate of speed determined by the setting of mounted in this bracket is a bar 56. A vernier the valve 18. adjustment it enables a delicate and precise ad- Dumping valve 33 is arranged to be controlled justment to be made of the longitudinal position 20 by the 3-way pilot valve 13 which is identical in of the bar relative to the platen, a rough adall respects with the pilot valve N shown in justment being provided by the adjustable condetail in Figure 6. The fluid outlet port of pilot nectlon between bracket 54 and the platen. Pivvalve 13 is connected with the control port 3| oted for rotation about a vertical axis on the of the dumping valve 33 by a conduit l5v Valve outer end of bar 55 is a bell crank lever 58 hav- 2:; I3 is provided with a. spring return fluid Dresing a hand grip portion U in which may be insure actuated plunger 86 and it should be apcorporated a thumb switch shown schematically parent that when fluid pressure is applied to port at El. The short leg of lever 58 is pivoted at I! II and the plunger is moved to inner position, to a link III which in turn is pivoted to a disk the port 34 will be connected with port 31 and II which is rigidly attached to the outer rotor I so consequently large volumes of fluid may pass diof the valve 28. Sufficient friction is provided in rectly from the supply line ll to the outer end the pivotal connections of the lever 58 toprevent of cylinder II to move the platen l6 rapidly. relative movement between parts 55, It and ill During this operation the large volume or fluid unless the operator manipulates the lever 58. required is furnished by the accumulator 2i.

Mounted on link 6' i a p ing loaded latch as Also during this operation, port 38 is connected I: which holds the toggle in straightened out with port I to allow the fluid in the inner end of condition as shown in Figure 2 and also mounted cylinder It to move rapidly to the sump 2|. In on the link 60 is a switch 63 and a 3-way pilot practice, the passages through valve or are quite valve 64, the operators of which are adapted to large and to prevent creepage or the platen a be engaged by a projection 65 of the lever 58. It so small bypass I1 is provided between ports 31 and should be apparent that if, in starting condition, 3|, the lever 56 is at rest in a position c nb rcl ck- Interposed in conduit is a T flttlng II and Wi ly rotated from its position shown in Figure 2. between fitting 88 and pilot valve 13 is a manual and i her f the l r s rotated in a kcontrolled valve 89. Interconnecting fitting ll Wise di e i the toggle 53 will e ext nded and and the outlet port ll 01' the pilot valve 84 is a the wi h 53 together wi the valve l be conduit N in which is positioned a manually conactuated. Also latch 62 will operate as indicated. trolled valve It,

Cam 5'. whi h i preferably constructed as Disk I which is rigidly connected with the h wn in d l in res 7, 8 and 9. is piv lly so outer rotor ll of the valve 18 is provided with a n d at 6 to a slide 61 hich is guided in yoke 92 within which is positioned the spring the flxed guide it A V n adjustment 3! is pressed thimbles 93 carried by the lever 52. The provided to enable a ilnal adjustment to be made purpose 1' mm balancing of the angula rela n between he m d the the inner and outer rotors of the follow valve I. slide. Slidably mounted on the slide 81 is an 13 t normally i t i th rotors i their 1 actuator a ri r e p si i n of Which may tive positions shown in Figure 4. With the parts he minu ely di d y th r w It T r dassembled and in their relative positions in Figedly received in the carrier 10 is a screw 12 which ure 2,11; should be apparent t u is adapted to engage e ope g plunger of and movement of the cam II in the forward direction, to pera -way Pilot valve 1!. Carrier 10 the rotor 40 will be rotated counterclockwise and also mounts a screw H which is arranged to fluid pressurewill be admitted to es It and a e 8 Switch 41 and thence to port 8| to move platen II toward Referring now to Figure 1, the slide carrying platen ll. As the platen II moves it rotates rotor the cam 60 is moved by a cylinder 16 which has 4| and when es l8 and 41 are again closed its rod end connected directly with the fluid supoil' by the shoes 48 the movement stops. Thus ply lin 10. The other end of the cylinder ll the platenis normally caused to move at a rate is connected with the fluid supply line through of speed which is determined by the pitch of the th 3-way pilot valve 64 and an adjustable needle portion of the cam II which at the instance is valve ll. Valve it has an inlet port 19, an outlet engaged by the follower on the arm ii. The cam port I0 and a return port II and is shown in deis moved at a constant predetermined rat of tail in Figure 6. It is provided with a plunger 82 7 speed as determined by the setting or the needle and it should be apparent that upon the inward valve II and the advanced position reached by th movement of the same the port I! is connected platen II at any particular time is determined with the port ll to allow fluid to flow through by the lateral position of that portion of the cam the needle valve II and into the cylinder II. which is engaged by the follower at the time be- When the plunger is retracted the port 00 comcause of the interconnection between the platen position and velocity ratio,

. is controlled. It should be apparent that a very flne adjustment of the velocity of the platen may be achieved by manipulating the screw 69 which varies the angular relation of the cam 60 relative to its line of travel. To provide a wider range of adjustment or to vary the pattern of the time or the camis preferably constructed in the manner now to be described.

Referring now to Figures 7, 8 and 9, cam ill is made up of a multiplicity of laminations 85 each needle valve II and the cam ll now moves forwardcausingthe slide lltomoveaccordingtoa predetermined pattern during flashing. The flashing time is, of course. determined by the setting of the metering valve II and when the cam carrier l1 reaches a predetermined advanced position, the screw operates-pilot valve 13 ,which in turn operates dumping valve 33 to cause fluid to consisting of a flat plate having spaced upwardly extending projections 90, the interval between which is substantially equal to the diameter of the cam following roller of the machine with which the cam is used. Laminations 95 are as sembled on a plate 91 having an upwardly extending shoulder at either end thereof. The shoulders are notched at their ends to accommo date retaining bars 88 which are secured to the plate 81. Laminations 95 are clamped in position by screws 99 which extend through one of the shoulders of the plate 91. When the screws are tightened the laminations are rigidly held in their proper relative positions and, in practice, the cam is setup by employing a template to give the desired contour to the cam surface. It should be apparent that a wide variety of cam forms may be readily achieved and that by employing the proper template for the particular operation which the machine is set up to perform, the crit-I ical problem of securing the proper flashing movement of the platenis overcome. A bolt 68 pivotally mounts the cam on the carrier 81.

As is well understood in the art it is common flash welding practice to move the edges of the stock into engagement with each other and to allow current to flow therethrough to preheat the edges of the stock before the start of the welding cycle proper. This operation is preferably a manually controlled operation and the present inven tion enables it to be readily accomplished without disturbing any adjustments which are of a critical nature as regards the functioning of the welding cycle proper. In the illustrated embodiment thumb switch, when closed, starts the flow of current through'the primary of transformer l'l, switch 62 being in parallel with switch 58 and switch 15' being the current cut-ofl switch. Assume that the slide it is in retracted position, the operating lever 68' in the dotted line position of Figure 2, and the slide 61 in its initial starting position so that the follower is at the end A of the cam, movement of lever 56 in a clockwise direction rotates rotor ll likewise and thus the edges of the stock clamped in the platens may be. brought into engagement. The desired amount of preheating current is applied by closing switch ll after which the switch is opened and the, lever it moved oppositely to return platen l5 and all the parts to their initial starting positions to commence the start the welding cycle proper.

With or without reheating the welding cycle is initiated by moving lever 56 clockwise from its dotted line position of Figure 2 and simultaneously closing switch 58. If the operation is to be entirely automatic, the operator moves the lever a sufflcient amount to engage latch 62 and since switch 63 is in parallel with switch 58 and is closed when lever 56 is latched by 62, the oper ator may then release switch 58. Arm 66 of lever 58 also actuates pilot valve 64 which, as stated flow into cylinder It at a high rate to'effect a quick upsetting of the highly heated edges of the stock held in the platens. At an adjusted interval after or before the beginning of the upsetting movement the screw ll actuates switch 1! to cut oil the flow of current to the welding transformer l1. After the work is unclamped from the electrodes, lever 56 is moved counterclockwise to open switch 63 and to release the plunger of pilot valve 64, which latter now connects its port It with its port Ii .to allow fluid to move from the closed end of cam cylinder ll through the -check valve l4 and a conduit I! back to the sump 2i. Fluid enters the rod end of cylinder It to rapidly move the cam 50 outwardly to its initial starting pomtion. ,As the cam 50 begins its outward or backward movement, the pilot valve I3 is released and plunger is of valve 33 is spring pressed outwardly to its normal position. Return movement of the platen ii is controlled by the cam 50 which, of course, moves faster on its return stroke because the needle valve 18 is then bypassed by the line I.

An important feature of the present invention is the attainment of flexibility but simplicity of control while retaining the primary vantage of the use of precision devices resulting in optimum performance characteristics. The control may be readily arranged for manuaLsemi-autounder the control of the pilot valve 64, which, of

' its proper amount, valve "is opened, and valve above, supplies fluid to cam cylinder 16 through 1 course, can be actuated at any time at the will 'of the operator by moving lever lit a suflicient amount in a clockwise direction. Needle valve II is also closed for manual operation to prevent operation of the cam it so that the flashing movement is under the sole control of the operator through lever 56. For semi-automatic and automatic operation, the needle valve l8 is opened at is closed. In semi-automatic operation, .the flashing or at least the initial part of the flashing phase of the cycle is manually controlled through lever -58 since cam cylinder It is not actu-' ated until pilot 64 is engaged, but at any time in the phase the operator may throw lever 56 into latched position shown in Figure 2 and from then on thecycle is automatically controlled.

The final die (electrode) interval or dimension is determined by the setting of nut 20 and the initial die opening is determined by (a) the lateral position of the cam groove at end BIA and (b) the adjusted position of the bracket 54 and the adjustment 66. The flashing interval is determined by (a) the shape and/or angular disposition of the cam 50, and (b) the adjustments H and 12. The upsetting interval is, of course, the distance remaining and this interval may be adjusted, per se, roughly by moving the bracket 54 or flnely by vernier adjustment 58. Screw It provides a coarse adjustment of the flashing and the current cut oil points and these variables may be individually adjusted by the screws 12 and Il. It should be apparent that this arrangement enables the current to be cut off when desired after 'termined advanced assassin rangement also enables an adjustable time delay upsetting and the time of current cut on which feature has, in certain welding operations, been proven quite desirable.

The above specifically described embodiment oi the invention should be considered as illustrative only as obviously many changes may be made therein without departing from the spirit or scope of the invention. Reference should therefore be had to the appended claims in determining the scope of the invention.

What I claim is:

1. In a flash welder having a normally fixed platen and a movable platen, means to control the movement of the movable platen during the welding cycle comprising in combination a source of hydraulic fluid under pressure, a fluid pressure operated motor for moving said movable platen, a follow-up valve means for metering the flow of fluid from said source to said motor, said valve means having two relatively movable valve elements one of which is adapted to be connected to said movable platen. means to control the movement of the other of said valve elements in such manner that the movement of said platen will follow' a predetermined position-speed relationship during the flashing period 01' said cycle, a second valve in parallel with said first valve and being operative to conduct quickly a relatively large volume of fluid from said source to said motor, and means to actuate said second valve after the termination of said flashing period to effect the upsetting of the edges of the pieces to be joined.

2. In a flash welding machine having a normally fixed platen and a movable platen. a source of hydraulic fluid under pressure, a fluid pressure operated motor for moving said movable platen during the welding cycle, a follow-up valve means for metering the flow of fluid from said source to said motor to eflect movement of the movable platen during the flashing period of the welding cycle, said valve means having two relatively movable valve elements one of which is adapted to be connected to said movable platen. a time controlled cam in control of the movement or the other of. said valve elements to efi'ect a predetermined time-position relationship in said movement, a second valve to quickly pass a relatively large volume of fluid to said motor to effect a quick upsetting movement in said movable platen. and means responsive to a predeposition of said cam to actuate said second valve.

3. In a flash welder having a normally fixed platen and a movable platen, a source of hydraulic fluid under pressure, a fluid pressure operated motor connected to said movable platen for moving the same, a valve having two relatively movable elements for metering the flow of fluid from said sourceto said motor, one of said elements being adapted to be moved in synohronism with said platen while the other of said elements is arrans ed to be moved by a control member, the arrangement being such that said movable platen follows the movement of said control member, a second valve in parallel with said first mentioned valve and being operative to quickly pass a relatively large volume of fluid from said source to said motor to effect a quick upsetting movement in said movable platen, and means responsive to the advanced position or said control member to actuate said second valve.

4. In a flash welder having a normally fixed time controlled cam .with said platen and platen and a movable platen, a fluid pressure on erated motor connected to the movable platen for moving the same, a follow-up valve for metering the flow of fluid to said motortoimpart movement to said movable platen during the flashing period of the welding cycle,. said valve being mechanically coupled with said platen and with a movable control member whereby the platen will follow the movement of said control member, a time controlled device for moving said control member, a second valve in parallel withsaid differential valve and of larger capacity than said diiferential valve to quickly pass a relatively large volume of fluid to said motor, and means to actuate said second valve upon said platen reaching a predetermined advanced position.

5. Apparatus for moving the movable platen in a flash welding machine comprising a fluid prespressure, means to control the flow of fluid from said source to said motor comprising a follow-up valve having two controlling elements one or which is connected with said movable platen, a connected with the other of said movable elements, a dumping valve in parallel with said follow-up valve, and means responsive to the advanced position of said cam to open said dumping valve whereby a large quantity of fluid is transferred from said source to said motor to effect a quick upsetting movement of said platen.

6. Apparatus according to claim 5 further including an adjustable linkage between the said said elements and the linkage including a manually operable lever whereby the follow-up valve may be actuated to eifect movement of said platen independently of movement of said cam.

7. Apparatus according to claim 5 further including an adjustable linkage between the said one of said elements and said platen, said linkage including a manually operable lever whereby the follow-up valve may be actuated to move said platen independently of movement of said cam, means to move said cam, and means responsive to the relative position of said lever in said linkage in control of the means to move said cam.

8. Apparatus for controlling the movement or the movable platen of a flash welding machine having a fluid pressure operated motor connected with said platen and a source of hydraulic fluid under pressure comprisin in combination a valve to meter the flow of fluid to said motor to eflect movement of said platen during the flashing period of the welding cycle, a, manually controlled lever to actuate said valve, a dumping valve in parallel with said first mentioned valve to transfer fluid to said motor at a substantially higher rate to effect a quick upsetting movement 01 said platen, and means actuated upon said lever reaching an advanced position to open said dumping valve.

9. Apparatus for controlling the movement 02 the movable platen of a flash welding machine having a fluid pressure operated motor connected 7 av source of. hydraulic fluid under pressure comprising incombinationa valve to meter the flow of fluid to said motor to eflect movement of said platen during the flashing period of the welding cycle. a manually operable bell crank lever pivotally connected to said platen and having its short leg pivotally connected with a link coupled with said valve, a dumping valve in parallel with said first mentioned valve transfer fluid to said motor at a substantially higher rate to effect a quick upsetting movement of said platen, and means actuated upon continned rotation of said lever in one direction to open said dumping valve.

10. Apparatus according'to claim 9 further including means to vary the longitudinal position or said flrst mentioned pivotal connection relative cycle, said valve comprising two relatively mov-' able rotors, a movable cam to rotate one of said rotors according to a predetermined time-position pattern, a toggle linkage connecting the other of said rotors with said platen and in-' eluding a manually engageable lever, a resilient balancing. interconnection between said rotors,

means to move said cam at a predetermined rate of travel, means to latch said lever in a predetermined relative position, and means operable when said lever is in latched position to actuate said means to move said cam.

12. Apparatus according to claim 11 iurthe including a dumping valve in parallel with said flrst mentioned valveto eiiect a quick upsetting movement of the said platen, and means responsive to the advanced position of said cam to open said dumping valve.

13. Apparatus according to claim 11 further including a switch arranged to be actuated when said lever is in latched position and adapted to maintain the flow of welding current to said platen, and a second switch arranged to beactuated upon said cam reaching a predetermined position to interrupt the flow of welding current.

14. Apparatus for controlling the movement of the movable platen of a flash welding machine having a fluid pressure operated motor connected with said platen and a source or hydraulic fluid under pressure comprising in combination a follow-up valve to meter the flow o1 fluid to said motor to effect the movement of said platen, said valve comprising relatively movable control elements one of which is connected with said platen through linkage means, a manually engageable control lever to vary the eflective length of said linkage means, means to move the other of said elements comprising a movable cam adapted to be moved at a consstant predetermined rate oi travel to eflect a predetermined time-position pattern in the movement of said platen, and means to vary the pattern of said 15. Flash welding apparatus having a movable platen, is source of fluid under pressure, a fluid pressure operated motor connected to said platen, a follow-up valve for metering the flow oi fluid to said motor to eflect flashing movement in said platen, a dumping'valve in parallel with said follow-up valve to efl'ect a quick upsetting movement in said platen, means to actuate said follow-up valve according to a predetermined timeposition pattern, a manual control lever, means responsive to a restricted movement of said lever to actuate said follow-up valve independently of said time-position means, means responsive to further movement of said lever to actuate said asvaaae A to the advanced movement or said last mentioned means to open said dumping valve, means to render said time-position means inoperative. and means to render said means responsive to the further position of said lever operative to op n said dumping valve.

18. In flash welding'apparatus having a movable platen and means to supply welding current thereto the combination or means to move said platen at a relatively slow rate of movement during the flashing period of a welding cle and to thereafter impart a quick upsetting movement to said platen, means to interrupt the flow of welding current, means to actuate said interrupting means in timed relation with respect to the time of the beginning 01' said upsetting movement, and means to vary the time interval between said interruption and said initiation or upsetting movement. I

17. Apparatus for controlling the movement of a movable platen of a flash welding machine having a fluid pressure operated motor connected with said platen and a source of fluid under pressure comprising in combination a follow-up valve means to meter the flow or fluid under pressure to said motor, said valve means having a movable control element, a manually engageable lever for moving said control element, said lever being pivotally mounted on said movable platen, said valve means having a second movable control element arranged to coact with said flrst mentioned element, and means to move said second element according to a predetermined pontiontime pattern.

'18. Apparatus for controlling the movement of a movable platen of a flash welding machine having a fluid pressure operated motor connected with said platen and a source of fluid under pressure comprising in combination a follow-up 4. valve means to meter the flow oi fluid to said motor and having a movable valve control element, an operating link connected to said element, a manually engageable lever pivotally connected to said movable platen and having a portion mechanically connected with said link, said valve means having a second valve control element arranged to coact with said flrst mentioned control element, means to move said second contion-time pattern, and means operative upon said lever reaching a predetermined advanced position to initiate the operation of said means to move said second element.

19. Apparatus according to claim- 18 further including means to supply welding current to said platen, and means operative upon said second mentioned element attaining a predetermined advanced position to interrupt the flow oi curtrol member, means to move said control memher, said follow-up valve having a second control member adapted to be moved relative to said first mentioned control member, a toggle intertime-position means, means normally responsive connecting said second control member and said trol element according to a predetermined .posimovement of said platen during the 11881111111301 10 tion of theweldin: cycle, a dumping valve in parallel with said first mentioned valve to quickly transfer a. large volume 01' fluid from said accumulator to said motor to provide for a. quick tuate said dumping valve.

C YDE E. COATES. 

